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S P Kernodle

Publications and source records attributed to S P Kernodle.

5 recordsLinked to original sources
PubMed2007

Analysis of an introgressed Nicotiana tomentosa genomic region affecting leaf number and correlated traits in Nicotiana tabacum.

Germplasm from closely related diploid relatives of tobacco (Nicotiana tabacum L.) could be of value for continued genetic modification of this species and for mapping quantitative trait loci (QTLs). We examined near isogenic tobacco lines and hybrids differing for an introgressed genomic region from N. tomentosa Ruiz and Pavon designated as Many Leaves that exhibits a large influence on leaf number and correlated traits. Within a 'Red Russian' genetic background, the region acted in an additive to partially dominant fashion to delay flowering time, and increase leaf number, plant height, and green leaf yield. Evidence of epistasis was observed as the region affected these traits to varying degrees in diverse near isogenic hybrids. Fifteen amplified fragment length polymorphism (AFLP) markers of N. tomentosa origin were mapped within a single linkage group of 34.5 cM using a population of 207 BC(1)F(1) individuals segregating for Many Leaves. Composite interval mapping produced 2-LOD confidence intervals for likely QTL positions influencing leaf number (3.1 cM region), plant height (2.9 cM region), and days to flowering (3.3 cM region). These intervals were overlapping. Results demonstrate that genomic regions with large genetic effects can be transferred to tobacco from closely related diploid relatives, and that sufficient recombination within these regions may permit mapping of genes controlling quantitative traits. Materials and results described here may be useful in future research to gain insight on the genetic control of the transition from vegetative to reproductive development in Nicotiana.

Amplified Fragment Length Polymorphism Analysis↗
PubMed2001

Structural organization, regulation, and expression of the chloroplastic superoxide dismutase Sod1 gene in maize.

A cDNA and genomic clone encoding maize chloroplastic Cu/Zn superoxide dismutase Sod1 were isolated. Southern blot analysis indicated little homology between the chloroplastic (Sod1) and the cytosolic (Sod2, Sod4, Sod4A) cDNAs. Sequence analysis of the genomic clone revealed a promoter, transit peptide, and partial coding sequence. The promoter contained several response elements (e.g., for light, cold temperature, xenobiotics) that may be involved in the regulation of the Sod1 gene. Sod1 expression during development and in response to physiological and chemical stressors such as temperature, xenobiotics (paraquat), and light were examined.

Amino Acid Sequence↗
PubMed2001

Differential antioxidant responses to norflurazon-induced oxidative stress in maize.

This study examined the contribution of catalase (CAT) and superoxide dismutase (SOD) in the overall antioxidant response to norflurazon (NF)-induced oxidative stress in leaves, mesocotyls and scutella of maize (Zea mays). Maize catalase null mutants were used to provide insights into the role(s) of these isozymes. A substantial increase in Cat1 and Cat2 transcript levels occurred in NF-treated leaves in all maize lines examined. However, these two transcripts did not show a particular pattern of change in NF-treated scutella from 5-day postimbibition (dpi) and 18-day postpollination (dpp) maize. The NF-induced increase in Cat1 appeared to be dependent on excessive light energy caused by a lack of photoprotectant carotenoids. especially in leaves. In NF-treated leaves, the chloroplastic Cu/Zn-SOD-1 isozyme responded strongly compared to the cytosolic Cu/Zn-SOD and mitochondrial Mn-SOD-3 isozymes, suggesting the critical role of SOD-1 as a major component in chloroplastic antioxidant defenses. All SOD isozymes in the NF-treated scutella of various maize lines were consistent in their response to NF. The most significant increase was observed with Sod1 in NF-treated leaves; however, no significant Sod1 changes were observed in similarly treated scutella at 5 dpi and 18 dpp. These results suggest that the response of the Cat and Sod genes to NF is likely developmental and tissue-specific.

Antioxidants↗
PubMed1996

A comparison of the structure and function of the highly homologous maize antioxidant Cu/Zn superoxide dismutase genes, Sod4 and Sod4A.

Two highly similar cytosolic Cu/Zn Sod (Sod4 and Sod4A) genes have been isolated from maize. Sod4A contains eight exons and seven introns. The Sod4 partial sequence contains five introns. The introns in both genes are located in the same position and have highly homologous sequences in several regions. The largest intron (> 1200 bp) interrupts the 5' leader sequence. The presence of different regulatory motifs in the promoter region of each gene may indicate distinct responses to various conditions. Zymogram and RNA blot analyses show that Sod4 and Sod4A are expressed in all tissues of the maize plant. The developmental profiles of Sod4 and Sod4A mRNA accumulation differ in scutella during sporophytic development. RNA blot analysis of the respective Sod mRNAs indicates a differential, tissue-specific response of each gene to certain stressors. RNA isolated from stem tissue of ethephon-treated seedlings shows an increase in the Sod4 but not the Sod4A transcript while there is no change in transcripts of either gene in leaves or roots. There is differential mRNA accumulation between the two genes in leaf and stem tissue of paraquat-treated seedlings. Other agents that can cause oxidative stress were also tested for differential expression of the genes.

Amino Acid Sequence↗